The Retail Motor Industry Federation (RMIF) is asking the government to complete its consultation period over MOT testing and to publish the results of the investigations.
The Department for Transport (DfT) has been deliberating over extending the period for new cars to be exempt from testing from three years to four, and then to only require compulsory testing every 24 months instead of the current annual check.
Stephen Coles, head of MOT operations for the RMIF, says: "A move from a 3-1-1 testing programme to a 4-2-2 will mean that many cars will not need to be tested.
"With less custom coming through their doors, we will see thousands of MOT testing stations forced to shut down, and many thousands of qualified testers made redundant, perhaps half of all the testers in the UK. As the MOT test is a legal requirement for vehicle owners, the fallout from this for consumers could be disastrous. When motorists would need an MOT, they would be unable to get one performed, which would have a knock-on effect on their ability to tax and insure their vehicles."
The DfT MOT Consultation has already been delayed several times. It has also been considering changes to the fee structure.